4 beads and 1 marble cost $11.80.
1 bead and 4 marbles cost $18.70.
- Find the cost of 1 bead and 1 marble.
- Find the cost of 1 marble.
- Find the cost of 1 bead.
- Find the cost of 5 beads and 5 marbles.
(a)
4 beads + 1 marble = 11.80 --- (1)
1 bead + 4 marbles = 18.70 --- (2)
(1) + (2)
5 beads + 5 marbles = 11.80 + 18.70
5 beads + 5 marbles = 30.50 --- (3)
(3)
÷ 55 beads + 5 marbles = 30.50
1 bead + 1 marble = 30.50 ÷ 5
1 bead + 1 marble = 6.10 --- (4)
(b)
(2) - (4)
(1 bead + 4 marbles) - (1 bead + 1 marble) = 18.70 - 6.10
1 bead - 1 bead + 4 marbles - 1 marble = 12.60
3 marbles = 12.60
1 marble = 12.60 ÷ 3 = 4.20
Cost of 1 marble = $4.20
(c)
Substitute 1 marble = 4.20 into (4).
1 bead + 1 marble = 6.10
1 bead + 4.20 = 6.10
1 bead = 6.10 - 4.20 = 1.90
Cost of 1 bead = $1.90
(d)
(4)
x 5 1 bead + 1 marble = 6.10
5 x (1 bead + 1 marble) = 5 x 6.10
5 beads + 5 marbles = 30.50
Cost of 5 beads and 5 marbles = $30.50
Answer(s): (a) $6.10; (b) $4.20; (c) $1.90; (d) $30.50